Unlike most chronic renal diseases, in which the female gender is a protective factor, this "female advantage" is lost in diabetes as diabetic females develop more renal disease than non-diabetics; we propose that this is due to low levels of plasma estradiol (E2) in diabetic females. The findings suggest that estrogens (including E2 and its metabolites, such as 2-methoxyestradiol (2-ME)) contribute to the pathophysiology of diabetic renal disease. Based on our preliminary data, we hypothesize that: Specific Aim 1: E2 regulates the renal renin-angiotensin system by reducing the expression and activity of the RAS: specifically by 1. tonically downregulating AT1Rs, 2. decreasing Ang II and renin levels, 3. increasing AT2Rs and consequently attenuating the renal functional and structural changes (in particular vascular changes) associated with diabetic nephropathy. Specific Aim 2: E2 and an estrogen metabolite 2-methoxyestradiol (2-ME) attenuate oxidative stress associated with diabetic nephropathy by reducing NADPH oxidase activity and NADPH oxidase-induced O2.- generation in the diabetic kidney. Specific Aim 3: E2 and 2-ME attenuate inflammation associated with diabetic nephropathy by reducing 1. Acute inflammation and markers of the acute phase inflammatory reaction: IL-6, MCP-1 and M-CSF; 2. Chronic inflammation: vascular permeability, migration and infiltration of inflammatory cells in target tissues; 3. glucose and AT1R-mediated Ang ll-induced NF-kB expression in target cells and resultant 4. NF-kB- induced TGF-b protein expression and subsequent activation of the Smad signaling pathway. Specific Aim 4: E2 and 2-ME attenuate glomerulosclerosis and tubulointerstitial fibrosis associated with diabetic nephropathy by 1. Reducing hyperglycemia/Ang ll-induced cell growth and ECM protein synthesis, namely collagen type I and IV, laminin and fibronectin, 2. Increasing ECM protein degradation, by increasing the activity and expression of matrix metalloproteinases, MMP-2 and MMP-9. The findings from these studies will provide insight into the mechanisms by which estrogens contribute to the pathophysiology of diabetic nephropathy and may stimulate novel ideas for developing gender-specific treatment modalities for diabetic nephropathy. [unreadable] [unreadable] [unreadable]